نتایج جستجو برای: diversity of vegetation density
تعداد نتایج: 21214870 فیلتر نتایج به سال:
The Chinese Loess Plateau region has long been suffering from serious soil erosion. Thus, large-scale afforestation has continued during the past decades in order to control soil erosion. Afforestation can dramatically alter nutrient cycles, affect soil-carbon storage, and change hydrology. However, it is unknown how afforestation influences species diversity of the soil seed bank and understor...
survey on zooplankton composition was studied during june 2015 to march 2016, by selecting six stations along the coastal waters of bushehr (the northwest persian gulf). twenty four zooplankton taxa were identified, and the different zooplankton groups represented twenty-one families. copepoda was recorded with the most abundance (53.30 %) followed by malacostraca (32.87 %), which in turn was f...
Livestock grazing practices in rangelands are being recognized as management tool for environmental protection and increased livestock productivity. Continuous grazing has been largely reported to reduce pasture productivity and increase environmental degradation. Rotational grazing is an alternative to continuous grazing and is considered to reduce negative environmental effects and provide qu...
درک الگوی توزیع مکانی ماکروفون خاک بدلیل اثرات آن روی فرآیندهای اکوسیستم بسیار مهم است. لیکن اطلاعات کمی در این خصوص وجود دارد. درمورد تنوع زیستی ارگانیسم ها وجانداران خاکزی که ازاجزای مهم وکلیدی درهرسیستم اکولوژیکی هستند و در بهبود حاصلخیزی خاک و تولیدات زمین وپایداری اکوسیستم ها(ازطریق فرآیندهای بیولوژیک)نقش عمده دارند تحقیقات کمی انجام شده است. این تحقیق جهت بررسی الگوی مکانی پارامترهای تنوع...
In order to investigate the effects of range management plans on species diversity, richness and evenness in Semirum rangelands, 52 sites (28 with treated plan and 24 without treated plan) were selected. The non-parametric indices for species richness (Margalof, Menhinick, Jacknife and counting method) and species diversity (Simpson, Camargo, Smith and Wilson and modified Nee) were compared in ...
The study of plant communities is the best way to learn about vegetation structure and distribution as well as various interactions among the plants in an ecosystem. Elevation factor plays a vital role in plant distribution that ultimately leads to specific phytogeographic regions. This study evaluated the changes in species composition, density, frequency, canopy cover and palatability of spec...
Effect of fire on phyto-sociology of understorey vegetation in chir pine forests of three different silvological characteristics was compared with pure grassland. 15 grasses, 1 sedge, 5 legumes and 21 non-legumes were recorded in the four study sites. Floristic composition gradually increased from June to August and then declined slowly by October in all the plots. Maximum number of species wa...
This study aims to assess the effect of grazing intensity on vegetation structure, soil nutrient concentrations and soil physical properties. The study was carried out in steppe rangelands of Saveh, Markazi province, Iran. Four sites with four grazing intensities including very high, high, moderate and non-grazed with the same ecological conditions were selected. To study various vegetation and...
this study aimed to investigate the effect of habitat kind on soil seed bank characteristics viz. density diversity, richness and similarity between seed bank and above ground vegetation. two different habitats (grassland and forest) were selected in vaz, mazandaran province. the grassland habitat located in the upper end of the forest habitat, adjacent to each other. then in each habitat, 7 tr...
Rangelands in Saudi Arabia extend over more than 175 m.ha. (about 75% of country land area) while woodland forests occupy only 2.7 m.ha. and are limited to the south western highlands. The diversity in landscape has been reflected in terrestrial plant species diversity. Range vegetation as well as forest understory vegetation has long history of grazing by livestock and wildlife herbivores. In ...
نمودار تعداد نتایج جستجو در هر سال
با کلیک روی نمودار نتایج را به سال انتشار فیلتر کنید